A stator of a motor generally includes a stator core made of a magnetic material, which includes an axially extended inner hole to receive a rotor. Generally, the stator core is made by stacking up and arranging multiple similar sheets in a frame and fixing them with a clamp or riveting them through projected points. A plurality of coils formed by insulated conductive wires are inserted into determined stator cavities in the stator core to render the coils to form U-turn areas in the end portion of the stator core. The coils are connected to one another to form coil assemblies or poles. The coils forming the so-called stator winding are usually covered with paints or enamels to form protective covering layers at the periphery of the coils, so as to form better insulation among the coils.
The coil assemblies included by a single-speed motor establish at least one set of winding. The coil assemblies are wound by a winding machine and are disposed on a coil inserting jig. The formed coils are inserted into the stator through for example the inserting jig subsequently, and therefore the coils are substantially aligned with the core cavities in the stator core. However, the traditional winding method is divided into three stages. Three single phase coils are inserted into the core cavities in the positions spaced apart with angles of 120 degrees during each winding stage, and the positions of the core cavities inserted in each stage are staggered with one another. The inductance unbalance of the three phase inductance of the stator core completed by the traditional method usually exceeds 1%, for example 2-3%.
Therefore, the motor manufactured with the stator core completed by the traditional method suffers poor performance because of high inductance unbalance.
Accordingly, there is still a need for a solution which can solve the aforementioned problem of high inductance unbalance.